1. Field of the Invention
The present invention relates to a developing apparatus mounted to an image forming apparatus such as a copier, a printer and the like and, more particularly, it relates to a developing apparatus in which a gap is provided between an image bearing member and a developing sleeve.
2. Related Background Art
Conventionally, in electro-photographic image forming apparatuses utilizing an electro-photographic image forming process, a process cartridge system in which an electro-photographic photosensitive member (referred to as “photosensitive drum” hereinafter) and process means acting on the electro-photographic photosensitive member are integrated as a cartridge which can be mounted and dismounted with respect to the image forming apparatus has been adopted. According to this process cartridge, since maintenance of the image forming apparatus can be performed by the user himself without any service man or expert, operability can be enhanced considerably. Thus, the process cartridge system has widely been used in the image forming apparatus. Among the image forming apparatuses in which magnetic toner is used in the process cartridge, there has been adopted means in which ferromagnetic seal members (referred to as “magnetic seals” hereinafter) are disposed at longitudinal end portions of a developer bearing member (referred to as “developing sleeve” hereinafter) constituting a part of a developing apparatus in a non-contacting relationship to the developing sleeve so that toner is held by magnetic forces of the magnetic seals to prevent the toner from leaking outside the developing apparatus.
Further, for example, as disclosed in Japanese Patent Application Laid-open No. 9-218578, a developer scraping member (referred to as “scraper” hereinafter) having a function for removing or scraping off the toner from a surface of the developing sleeve before the toner held between the developing sleeve and the magnetic seals reaches a developing portion between the photosensitive drum and the developing sleeve and, at the same time, for gathering the removed toner toward a developing area (inside) has been used together with the magnetic seals.